Taipei, April 27 (CNA) Anti-nuclear protesters held a rally against the fourth nuclear power plant Sunday afternoon, saying that they would occupy the streets of downtown Taipei until the government responds to their demands. The protesters marched from Ketagalan Boulevard in front of the Presidential Office to Zhongxiao West Road in front of the Taipei Main Station, where they lay down or sat in the road, paralyzing traffic in an area usually thronging with cars and buses. According to police estimates, over 10,000 people took part in the rally, while the organizers claimed that around 50,000 participated. The demonstrators, many of whom wore yellow "anti-nuke" banners, were demanding that the government immediately halt construction of the fourth nuclear power plant in New Taipei's Gongliao District and decommission the existing three operating nuclear power plants. "We are demanding a environment free from nuclear power," said Chiang Chin-song, a mother of two children. The government should not try to extend the operations of the existing nuclear power plants, said the 42-year-old. Chiang said seeing the nuclear crisis in Japan in March 2011 was the main reason for her opposition to nuclear power, which she said could pose a serious threat to the people's safety. Another protester, Wang Hsi-chuan, described occupying the streets as a necessary move in order to make their voices heard by the government. Instead of nuclear power, the government should seek to make more use of solar power as a supply of energy, said Wang, 50, who added that he has been engaging in the anti-nuclear movement for many years. Wang also had a photo of hunger-striker Lin Yi-hsiung -- a former opposition Democratic Progressive Party (DPP) chairman who is well-known for his anti-nuclear efforts -- attached to his back. "We should thank Lin for his effort," Wang said while siting on Zhongxiao West Road as part of the occupation movement. Anti-nuclear activists and the DPP have held a series of anti-nuclear demonstrations since Lin started his hunger strike April 22 to protest against the fourth nuclear plant. As the rally went on, the administration of President Ma Ying-jeou and the ruling Kuomintang (KMT) agreed to halt construction of the fourth nuclear power plant with immediate effect.